Self-controlled carburetor



July s, 1941.

M. J. KITTLER SELF-CONTROLLED GARBURETOR Filed Oct. 30. 1939 RELAY 0R Cannuxnoa mm nu wo DR NT n 1M E .H MC L TD w XN :A A.. 8 M Z. 7 9 2 2 mi@ Si QNALYZER YLR. CURVE.

Patente'd July 8, `1941 UNITED STATES PATENT OFFICE I 2,248,090 sELmcoN'rRoLLED cAaunETon Milton J. Kittler, Detroit, Mich., assignor to George M. Holley and Earl Holley Application October 30, 1939, Serial No. 301,942

5 Claims.

The object of this invention is to automatically control the mixture ratio of an airplane engine by means of an exhaust gas analyzer.

In the drawing.:

Figure 1 shows the general layout of the invention.

Figure 2 shows in greater detail the automatic mixture indicator and controller.

Figure 3 shows the desired mixture ratio characteristics at various percentages of maximum power.

In the figures, I is the exhaust gas analyzer connected in the usual manner to the exhaust pipe II. The carburetor I2 is located in the ain inlet I3 immediately above the mixture outlet I4. 'I'he mixture is supplied to a supercharger I5 and is delivered through the inletpassages, one of which No. I5 is shown. A pipe I1 connects this air inlet passage I6 with Athe mixture indicator and controller, the casing for which is numbered 23. The mixture admitted through the passage I6 is admitted to the cylinder I8 which cylinder is connected to the crankshaft I9 driving the propeller 20, which is provided with the usual constant speed propeller mechanism 2|. The exhaust connection from the cylinder I3 is shown at 22.

The electricity for operating the exhaust gas analyzer is obtained from a cell 24 connected through a wire 25 with the exhaust gas analyzer I0. The current ilows from the exhaust gas analyzer through the conductor 26 to the mixture indicator and controller contained in thev casing 23, from which it iiows through either of the two wires 21 and 28 which lead into the relay or amplifier 29. The current for the amplifier is obtained from a battery 30 and the amplified current leaves through either of the conductors 3| or 32. Depending on which wire 21 or 23 is used, the current enters the motor 33 through either of the wires 3I or 32 which derespond to the The details of the mixture indicator and controller 23 are indicated in Figure 2.

In Figure 2, 23 indicates the casing and the three wires 26, 21 and 28 correspond to the three wires 26, 21 and 28 of Figure 1. The pointer'31 is moved by the exhaust gas analyzer and indicates on the scale l38 the mixture ratio. This mixture ratio in Europe is measured as 14 to 1, or 12 to 1, but in the United States, the mixture ratio is referred to as .07,f.08, etc. This figure refers to the fraction of a pound of fuel per pound ofair and is reciprocal of the figure used in Europe. The pointer 31 moves to corexhaust gas analyzer in the methodfdescribed in American patent to Hebler 1,860,541. The pipe 50 corresponds to the inlet passage 1 of the pipe 43 corresponds to the outlet 8 of the Hebler patent. A

When Athe needle 31 moves to the left, current is conducted to the conductor 2B and an amplied current is supplied to the motor 33 through the conductor 32, and the motor 33 turns the lever 34, link 35, and lever 36 in the direction making the mixture richer. When the needle 31 moves to the right, the reverse'happens and termines the direction of rotation of the motor and, through the movement of the lever arm 34 which is connected through the link 35 with the mixture control lever 36 and the carburetor I2, the mixture strength. The control lever 36 cor'- responds to the mixture control lever as marked Z in patent to Chandler 2,125,886. 'Ihese mixture ratio control devices usually operate by applying back suction, or suction 'existing between the throttle and the supercharger, to the carburetor float chamber where a noat is used. In the case of iioatless carburetors they are used as shown in the above mentioned patent. The carburetor throttleisoperated by a link 43.

the mixture is made leaner.

The result is that the location of the rod 33 carryingthe two contacts 40, 4I, which respectively engage withthe pointer 31, determines the mixture ratio within very close limits. AThis rod 39 is moved by the lever 42 kwhich is pivotally mounted in the box 23I and is connected to the rod 43 which is moved bythe aneroid barometer 44 contained in a housing 45. This housing 45 is subjected, through vthe pipe I1, to the pressure or vacuum existing in the pipe I6 leading to the inlet valve of the cylinder I3, depending on the position of the throttle valve.

Figure 3 shows the desired mixture ratio control. At 30% of the rated power, or 3000 pounds of air in a 1400 horsepower engine taking 10,000 pounds of air per hour, the mixture ratio stands at .071. This mixture ratio is maintained up to'an air now of 7000 pounds of air per hour, or 1000 horsepower or of maximum power. At that point, the mixture ratio is increasedrapidly until it reaches .11 at %'power, which is the take-of! power, the power necessary to leave the ground with the slightest possible delay. When climbing at less than 75% of maximum power,

the mixture is leaner` than is desired. To overcome this, a movable stop 46 operated by a lever 41, is provided. In the positionwshown, the stop corresponds to the mixture ratio .071. When the Hebler patent and the outlet lever 41' moves over to the right, the stop 4l rises and the mixture ratio then cannot be leaner than .085. The lever 42 is forcibly moved to the position shown in broken lines in Figure 2, and thel lever 41 is held in position by a ratchet.

Operation when the engine is operating with the lever u in the position shown in Figure 2, the depression in the air entrance i6 to the cylinder i8 is such that the pressure in the pipe I 'l acting on the aneroid barometer 44 -causes the rod 43 to move to the right against the stop 4 6. Therefore, when cruising lean the mixture ratio is kept constant at .071. When the lever 41` is moved to the right, the stop 46 is moved to theleit, and the-two contacts 4I and 4i are draggedover to the right, so that the mixture ratio is now held constant at .085. There is .suillcient gear reduction in the motor Il so that the mixture ratio does not hunt when the contact 4I is engaged by the pointer 31. Inother words, when the mixture is richer than desired, the arm 36 moves slowly to make the mixture lean, and when the tion engine having air inlet passages and a fluid fuel supply, of means responsive tothe chemical composition of the exhaust gas and to the density of the air at the inlet passage for automatically regulating the ratio between the rate at which the fuel is fed to the engine and the rate `at which air is supplied to the engine for the combustion of the gasoline.

2. The combination with an internal combus- I I tion engine having air inlet passages and a fluid fuel supply, of means responsive to the chemical composition `of the exhaust gases and of the a,a4a,ooo v density of the air at the inlet passage for automatically decreasing the ratio between the rate at which the fuel is fedv to the engine, and theI rate at which air is supplied for its combustion on a decrease in the Adensity of the air whereby the cruising lean mixture is leaner than the takeoir mixture.

3. In combination, an internal combustion engine having a supercharger, an exhaust pipe 'and a carburetor equipped with a throttle and a mixture control valve, a gas analyzer adapted to be operatively connectedto the exhaust pipe of the engine,'and including an indicating element, g an electrically controlled relay responsive to movements of `the indicating element, a power u nit operated by the electricity derived from the relay and connected to the mixture control valve,

' ness.

means responsive to the absolute air-fuel-mixture pressure at the air-fuel-mixture entrance to the engine for moving the mixture ratio indicating element and thus controlling the mixture ratio at the gllredetel'mlned by the Said density.

4. In combination with an internal combustion Y engine an exhaust pipe and a'carburetor equipped with a throttle valve and a mixture control valve, an electrically operated motor connected thereto, a gas analyzer adapted for operative vconnection with the exhaust pipe of the engine and including a movable element, the movement of which re' sponds to changes in the mixture ratio, two electrical contacts adapted to be engaged alter( natively'by said movable element and thus adapted to conduct electricity to said electrically operated motor to aiternatively'move said mixture .control valve in the direction to make the mixture rich and to make the mixture lean, means responsive to the density of the air-fuel-mixture at the point where it enters the engine for moving the two electrical contacts so that at maximum density the mixture ratio is at its maximum rich- Y 5. In a device as set forth in claim 4 in' which there is a movable st op adapted to limit the4 movement -of the two electrical contacts so as to establish a minimum mixture ratio below which the mixture cannot fall so long as the fuel supply is maintained.

MILTON J. KITTLER. 

